objectives Caesarean section (CS) can be life-saving for both mother and child, but in Nigeria the CS rate remains low, at 2.7% of births. We aimed to estimate the rate of CS and early neonatal mortality in Nigeria according to obstetric risk and socio-economic background and to identify factors associated with CS.methods We used the 2018 Nigeria Demographic and Health Survey, encompassing 33 924 live births within the last 5 years, to estimate the CS rate and early neonatal mortality rate (ENMR) by obstetric risk group, informed by the Robson classification. The CS rate and ENMR were assessed within each Robson group and stratified by socio-economic background. Logistic regression analyses were used to explore determinants of CS.results Almost three-quarters (72.4%) of all births were to multiparous women, with a singleton baby of normal birthweight, thus a low-risk group similar to Robson 3, and with a CS rate of 1.0%. CS rates in the two high-risk groups (multiple pregnancy and preterm/low birthweight) were low, 7.1% (95% CI: 5.2-9.7) and 1.8 % (95% CI: 1.4-2.4), respectively. The ENMR was particularly high for multiple pregnancy (175 per 1000 live births; 95% CI: 131-230). Greater number of antenatal visits, unwanted pregnancy, multiple pregnancy, household wealth, maternal education, Christians/Others versus Muslims and referral during childbirth were positively associated with CS.conclusion Inequitable access to CS is not limited to socio-economic determinants, but also related to obstetric risk factors, calling for increased efforts to improve access to CS for high-risk pregnancies.